Cisco Practice CCENT

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Bus Topology

having a main cable (known as a trunk) that all systems would connect to.

Ring topology

has all systems connected in acircle, or ring. The data travels around the ring with each system regeneratingthe signal so that it can move to the next system (also known as a node onthe network; a node is a system or device that exists on the network) in thering.

Star topology

The star topology is a network layout that involves using a central devicesuch as a switch as the connection point for all systems on the network.

Coaxial cable

Coax cable has a copper wire at the core that carries the data in the form ofan electrical signal. This copper wire is surrounded by insulation, which ismade up of a braided wire and metal foil that helps protect the signal fromoutside interference.

Thinnet

Coax type - RG-58

Connector - BNC

Max length - 185 meters (606 feet)

Diameter - 1⁄4"

Speed - 10 Mbps

Thicknet

Coax type - RG-8

Connector - Vampire tap

Max length - 500 meters (1,640 feet)

Diameter - 1⁄2"

Speed - 10 Mbps

Twisted-pair cabling

has eight wires divided into four pairs of wires, with each wire in a pair being twisted around one another throughout the length of the cable.

Category 1 (Cat 1)

Voice only

Category 2 (Cat 2)

Data

4 Mbps

Category 3 (Cat 3)

Data

10 Mbps

RJ-45

Category 4 (Cat 4)

Data

16 Mbps

Category 5 (Cat 5)

Data

100 Mbps

RJ-45

Category 5e (Cat 5e)

Data

1 Gbps

RJ-45

Category 6 (Cat 6)

Data

10 Gbps

RJ-45

Fiber-optic cabling

it has a glass or plastic core and it sends pulses of light that travel through the core.

Speed - 1+ Gbps

Max length - Over 2 km (6561 feet)

Connector - SC, ST, and LC

SMF (Fiber-optic)

uses a single ray of light to transmit the data. The ray of light is knownas a mode — hence the term single-mode fiber-optic cabling! SMF is thefiber-optic cable type used for long distances, such as 40 kilometers (131,233feet).

MMF (Fiber-optic)

sends multiple rays of light at a time, with each ray of light running ondifferent reflection angles. MMF is the fiber-optic cable type used for shortdistances, such as 2 kilometers (6,561 feet).

Fiber-optic cabling

Fiber-optic cabling has a number of different types of connectors that areused to connect a system to the cable media. Three popular connector typesfor fiber-optic cabling are the SC, ST, and the LC connectors.

Straight-through cable

The straight-through cable is the techie term for a normal twisted-pair networkcable that connects a system to a switch. The straight-through cable gets itsname because each of the eight wires in the cable retains its position withinthe cable from one end to another.

Crossover cable

Remember that crossover cables are used to connect similar devicestogether — such as two systems, two switches, or a system to a router.(They are both considered hosts on the network.)

Rollover cable

The rollover cable(also known as a console cable) is used to connect the serial port on your system to a router or switch so you can configure the router or switch. The rollover cable is normally a light-blue cable (I have also seen black rollovers) and is flat instead of rounded like a twisted-pair cable.The reason they call it a rollover is that all of the wires in the cable change positions from one end to another. For example, wire 1 on one end of the cable would be wire 8 on the other end of the cable.

CSMA/CD

access method to discuss isCarrier Sense Multiple Access/Collision Detection (CSMA/CD). Here is howCSMA/CD works: When a system wants to send data on the network, it firstsenses the wire to see if there is already data on the wire (see Figure 2-16) —if there is already data on the wire, it waits until the wire is free, but if thewire is free of traffic, the system goes ahead and sends the data.

Token passing

Token passing is a different approach to how systems can send data on thenetwork. With token passing, there is an empty packet (the token) thatcirculates through the network thousands of times a second. When a systemwants to send data on the network, the system has to wait for the token toreach the system.Once the token reaches the system, the system fills the token with data andflags the token as being in use. The token is then submitted back on thenetwork (with data in it) and is headed to the destination system.The benefit of token passing is that in order to send data you need to havethe token — because there is only one token on the network, it is impossibleto have collisions in a token-passing environment.

CSMA/CA

Another access method (though it has become less and less popular overthe years) is Carrier Sense Multiple Access/Collision Avoidance (CSMA/CA).When a system wants to send data on the wire, it first senses the wire to seeif any data is already on it. If the wire is free, the system sends an announcementon the wire letting everyone know it is about to send data in hopes thatno other system will send data when they see the announcement. After theannouncement is sent, then the system sends the real data. This is a methodof trying to avoid collisions.

10Base2

10Mbps and uses baseband transmission.

uses Thinnet coaxial cable.

10Base5

10 Mbps and also uses baseband transmission.

uses Thicknet coaxial cable.

10BaseT

The 10BaseT architecture changes things up a little by using a differentcable type and a different topology. 10BaseT uses Cat 3 UTP cabling,which runs at 10 Mbps, and uses a star topology. 10BaseT uses basebandtransmission and CSMA/CD as the access method.

Fast Ethernet standards

The big jump in network speed after 10 Mbps was to the 100 Mbps networkingstandards, known as the Fast Ethernet standards — all of which run at 100Mbps, use CSMA/CD as the access method, use baseband transmission, anduse a star topology. The difference between these Fast Ethernet standards isthe type of cabling used.The two popular forms of fast Ethernet are 100BaseTX and 100BaseFX.100BaseTX uses Cat 5 UTP cable, while 100BaseFX uses fiber-optic cabling.

Gigabit Ethernet standards

Network architectures that transfer information at 1 Gbpsare known to follow the Gigabit Ethernet standards and use a star topology,baseband transmission, and the access method of CSMA/CD.